The CAS Registry Mumber 250127-09-4 includes 9 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 6 digits, 2,5,0,1,2 and 7 respectively; the second part has 2 digits, 0 and 9 respectively. Calculate Digit Verification of CAS Registry Number 250127-09: (8*2)+(7*5)+(6*0)+(5*1)+(4*2)+(3*7)+(2*0)+(1*9)=94 94 % 10 = 4 So 250127-09-4 is a valid CAS Registry Number.